1. Field of the Invention
The present invention relates to an information recording/reproducing apparatus for recording and/or reproducing information on a recording medium and, more particularly, to an apparatus using a card- or sheet-like information recording medium as a medium.
2. Related Background Art
Typical conventional information recording/reproducing apparatuses of the type described above are optical and magnetic ones. An optical information recording/reproducing apparatus has received a great deal of attention since it has a large memory capacity. Other various media such as optical disks, optical cards, and optical tapes have been known as conventional media for recording/reproducing information using light. These conventional media have different features and advantages so that they are used according to individual applications. Among these conventional optical media, optical cards are expected to be more and more popular in a variety of applications in favor of easy fabrication, portableness, and easy access.
Various schemes for scanning an optical card with a beam are proposed. A beam spot is linearly reciprocated on a medium, and at the same time, the beam spot position is relatively moved in a direction perpendicular to the direction of reciprocal movement. This scheme requires a simple mechanism and an effective space on the medium is advantageously large.
An optical information recording/reproducing apparatus using this scheme is illustrated in FIG. 1.
Referring to FIG. 1, an optical card 1 is placed on a shuttle 5. A laser beam 4 is emitted from a laser 8. A collimator lens 9 is arranged at the output side of the laser 8. A polarizing beam splitter 10 is arranged below the collimator lens 9 along the optical axis thereof. An objective lens 11 is arranged immediately above the optical card 1 along the optical axis of the collimator lens 9. A .lambda./4 plate 30 is inserted between the polarizing beam splitter 10 and the objective lens 11. A combination of the polarizing beam splitter 10 and the .lambda./4 plate 30 allows transmission of the laser beam incident from the side of the collimator lens 9 so as to record information on the optical card. However, the combination inhibits transmission of the laser beam 4 reflected by the optical card 1 but reflects it in a direction perpendicular to the optical axis of the collimator lens 9.
A photosensor 12 receives the beam reflected by the polarizing beam splitter 10. The laser 8, the collimator lens 9, the polarizing beam splitter 10, the .lambda./4 plate 30, the objective lens 11, and the photosensor 12 constitute an optical head (a block surrounded by the broken line in FIG. 1). The optical information recording/reproducing apparatus also includes a preamplifier 13, an autofocusing servo 14, an autotracking servo 15, a decoder 16, an interface 17, a computer 18, an encoder 19, a laser driver 20, and a stepping motor 21. The stepping motor 21 drives the optical head 3 in a direction perpendicular to the drawing surface.
An endless belt 24 is looped between pulleys 22 and 23. The shuttle 5 is mounted on the belt 24 to support and fix the optical card 1 on the belt 24. The pulley 22 is mounted on a rotating shaft of the motor 26. The optical card 1 can reciprocate along a direction indicated by a double-headed arrow A upon rotation of the motor 26.
The information reproduction mode of the information recording/reproducing apparatus in FIG. 1 will be described hereinafter.
Referring to FIG. 1, the laser beam generated by the laser 8 is collimated by the collimator lens 9. The collimated beam passes through the polarizing beam splitter 10 and the .lambda./4 plate 30. The laser beam from the .lambda./4 plate 30 is focused by the objective lens 11 to form a laser beam spot on the optical card 1. A laser beam reflected by the optical card 1 is modulated according to the presence/absence of an information pit. The modulated beam is collimated by the objective lens 11 and reflected by the polarizing beam splitter 10. The polarized laser beam is then incident on the photosensor 12. The photosensor 12 detects the intensity of the modulated beam and converts it into an electrical signal. The electrical signal from the photosensor 12 is sent to the preamplifier 13. An output from the preamplifier 13 is sent to the autofocusing servo 14. A signal from the autofocusing servo 14 is supplied to an actuator (not shown). The actuator drives the objective lens 11 in a direction indicated by a double-headed arrow B so that a distance between the objective lens 11 and the optical card 1 is controlled to form a spot of the laser beam 4 on the optical card 1.
The signal from the preamplifier 13 is also supplied to the autotracking servo 15. A signal from the autotracking servo 15 is supplied to the actuator (not shown). The actuator vertically drives the objective lens 11 with respect to the surface of the drawing so as to focus the laser beam 4 at a predetermined position. Various systems of the autofocusing servo 14 and the autotracking servo 15 have been proposed. For example, the laser beam 4 is split into a plurality of beams by a grating or the like. An autofocusing or autotracking track is preformatted on the optical card 1. At least one of the beams is used to reproduce information. Other beams are used to extract autofocusing and autotracking signals.
The signal from the preamplifier 13 is supplied to the decoder 16 and is electrically processed. The processed signal is supplied to the interface 17. An information signal is supplied from the interface 17 to the computer 18. A signal is sent from the intcrface 17 to the encoder 19 and is properly modulated. The modulated signal is used to control oscillation of the laser 8 through the laser driver 20.
The interface 17 also supplies a signal to the stepping motor 21 and the motor servo 27 to control the vertical position of the optical head 3 with respect to the surface of the drawing and rotation of the motor 26.
It is very important to detect whether the card is properly inserted in the information recording/reproducing apparatus regardless of optical and magnetic cards. More specifically, if the card is inserted such that the recording medium surface does not contact the recording/reproducing head (to be referred to as reverse insertion hereinafter), or if the card is inserted such that the rear end is inserted first (to be referred to as backward insertion hereinafter), reverse or backward insertion must be immediately detected and the corresponding card must be dispensed outside the apparatus.
When reverse and backward insertion detecting means are separately arranged inside the apparatus, the number of components is increased to undesirably result in high cost, a bulky arrangement, and degradation of reliability.